1. Field of the Invention
The present invention relates to an Evolved Multimedia Broadcast Multicast Service (E-MBMS) service method and, more particularly, to an E-MBMS service method in which, in a current cell where MBMS control information is cyclically transmitted, a user equipment can receive MBMS control information of a neighbor cell only when the MBMS control information of a neighbor cell is modified.
2. Discussion of the Related Art
In Evolved-Universal Terrestrial Radio Access (E-UTRAN) of a Long Term Evolution (LTE)-Advanced system, only evolved-NB (eNB) in which the function of a Radio Network Controller (RNC) and the function of a base station such as a Node B (NB) in UTRAN are integrated is defined. An eNB cannot supply a user equipment with MBMS radio resource information about neighbor cells because it allocates MBMS radio resources to only cells covered by the eNB. Further, the eNB may not use soft combining or selective combining technologies which can be obtained using a soft handover characteristic based on Wideband Code Division Multiple Access (WCDMA) technology, because of a hard handover characteristic based on Orthogonal Frequency Division Multiple Access (OFDMA) technology.
Accordingly, if a user equipment that receives an Evolved-MBMS (E-MBMS) in an LTE-Advanced system moves to another cell, a problem in which an E-MBMS service is interrupted may happen. In particular, if a cell is changed in a Radio Resource Control (RRC)-IDLE state without a wireless connection between an eNB and the user equipment, the user equipment has to be synchronized with the changed cell, receive system information, and then receive MBMS control information based on the received system information. Accordingly, there is a probability that an E-MBMS service may be interrupted for a long time. If the transmission cycle of MBMS control information is not sufficiently short, a problem that an E-MBMS service is interrupted irrespective of a radio access mode of the user equipment may happen.
Accordingly, there is a need for a scheme in which a user equipment can receive the MBMS control information of a neighbor cell only when the MBMS radio resource information of the neighbor cell is modified so that the consumption of battery power can be minimized and an E-MBMS service is not interrupted even when the user equipment moves between cells.